1. Field of the Invention
The present invention in general relates to a parallel processing computer system which performs processings in parallel at machine language level. In more particular, the invention relates to a parallel processing computer system which is additionally capable of executing operations on the basis of the principle adopted in the so-called Von Neuman type computer system, a typical one of serial or sequential processing computers.
2. Description of the Prior Art
Most of the computers which are used at present are operative on the basis of the serial processing principle in accordance with the concept adopted in the Von Neuman type computer system. However, in view of the currently prevailing state in which the computers are employed increasingly in many and various industrial and commercial fields, there exists certainly a great demand for the availability of a computer which can perform processing at very high speed.
In this connection, it is noted that the Von Neuman type computer whose operation is based on the serial processing principle is not inherently suited for the execution of processings which are required to be performed at ultra-high speed. For attaining the high speed processing as demand, the computer should have the capability for performing a plurality of processings in parallel. Under the circumstances, studies and activities are now under way in an attempt to develop an ultra-high speed computer system which is based on the parallel processing principle. In reality, data flow computers, control flow parallel computers and others have already been proposed.
However, most of the hiterto known parallel processing computers suffer drawbacks that the sequence in which instructions are to be executed can not be definitely determined in contrast to the Von Neuman type computer which is inherently designed to execute processings in a deterministic manner, the parallel processing computer may encounter difficulty in the processing of certain input signals so that corresponding output signals can be produced within a predetermined time. Moreover, the processings which are intrinsically to be performed in series or sequence can not be executed by the parallel processing computer without lowering the operation speed in contradiction to the fact that the parallel processing computer has been developed with the aim to increase the operation speed.
Further, the parallel processing computer differs from the conventional computers of Von Neuman type in respect to the basic principle. So, there may arise such a situation that the replacement of the Von Neuman type computer by the parallel processing computer cannot be smoothly realized, particularly in the fields where a great amount of available software developed until now exert important influences on the efficiency of work to be accomplished by using a computer. In other words, the parallel processing computer is incompatible with the Von Neuman type computer in respect to the available software.